My research interests focus on how steroid hormones influence the development of brain structures and behavior. Neonatal exposure of steroid hormones influences sex-specific brain development (formation, neurogenesis and apoptosis) and changes brain functions and behavior (e.g., learning and memory). However, the cellular and molecular mechanisms of steroid hormone action in the brain still remain mostly unknown. In rodents, steroid hormones are critical for sexual differentiation of brain morphology and behavior during critical periods of development. Studies in the Australian songbird - zebra finches, suggest that in addition to steroid hormones, genes expression the development of sexual dimorphic song control nuclei. In zebra finches, only adult males sing and the song control nuclei are larger in males compared to females. Using cDNA microarray and in situ hybridization techniques, we identified several genes expressed highly in the forebrain of juvenile male zebra finches compared to females, and those sexually dimorphic genes were highly and specifically expressed in song control nuclei. Current research investigate (1) the development of song control nuclei under the manipulation of steroid hormones and genes expression, and (2) the effect of behavior (song learning and production) on brain plasticity.